EP0158888B1 - Disazo compounds, process for their preparation and their use - Google Patents

Description

The invention relates to disazo compounds, in particular disazo pigments and their preparation. For example, not only symmetrical but also asymmetrical disazo compounds can be produced in this way.

DE-OS 2 232 524 (GB-A-1370543) describes disazo pigments with 1,4-phenylenediamine as bisdiazo component and acetoessigarylidene and pyrazolones as coupling components. These disazo pigments are prepared by treating one mole of diamine with two moles of an enolized or enolizable ketomethylene compound in an organic solvent with nitrous acid or its esters. Because of their manufacturing process, in which both amino groups are diazotized, they are always symmetrical, so that there are two identical residues of the coupling components on the 1,4-phenylenediamine residue. It is disadvantageous that the compound is obtained by the known process with insufficient yields and also in a particle size which is generally unsuitable for use as a pigment. The known disazo compounds are also insufficient in their properties, in particular in terms of opacity and gloss, but also in terms of migration fastness, light fastness and thermostability. Therefore, they can e.g. B. for some plastic coloring, especially for polyvinyl chloride, polyolefins or for paints. An improvement in the fastness properties mentioned has repeatedly been required in order to be able to use pigments on this basis universally.

in der X und Y gleich oder verschieden sind und Wasserstoff, Brom oder Chlor, eine Methyl-, Methoxy-, Ethoxy-, Nitro-, Trifluormethyl-, Carbomethoxy- oder Carboethoxygruppe bedeuten, A¹ und A² jeweils Wasserstoff, eine Methyl- oder Ethylgruppe und Z¹ und Z² in 6- oder 7-Stellung des heteroaromatischen Ringsystems jeweils Wasserstoff, Brom oder Chlor, eine Methyl-, Methoxy-, Ethoxy-, Carbomethoxy-, Carboethoxy- oder Nitrogruppe darstellen, das dadurch gekennzeichnet ist, daß man Verbindungen der Formel 11

in der B eine Amino- oder Nitrogruppe ist und X und Y gleich oder verschieden sind und die oben genannten Bedeutungen haben,

• a) im Falle, daß B eine Aminogruppe ist, diese 1,4-Diaminobenzole in wäßrigem Medium monodiazotiert und mit einer Verbindung aus der Reihe der 5-Acetoacetylaminobenzimidazole der Formel 111
  
  in der A und Z jeweils die oben für A¹ und A² bzw. Z¹ und Z² angegebene Bedeutung haben, zur Aminoazoverbindung der Formel IV
  
  kuppelt, oder
• b) im Falle, daß B eine Nitrogruppe ist, X und Y die oben angegebenen Bedeutungen haben, jedoch keine Nitrosubstituenten darstellen, dieses 4-Nitroanilin diazotiert und die Diazoniumverbindung auf ein Benzimidazolonderivat der Formel III kuppelt, wobei A und Z die oben genannten Bedeutungen haben, aber keine Nitrosubstituenten darstellen und dann die erhaltene Nitroazoverbindung der Formel V
  
  zur Aminoazoverbindung der Formel IV reduziert und
• c) die jeweils erhaltenen Aminoazoverbindungen der Formel IV erneut diazotiert und auf eine gleich oder verschieden substituierte Verbindung der Formel III kuppelt und das erhaltene Reaktionsprodukt in üblicher Weise aufarbeitet und anschließend einer thermischen Nachbehandlung bei 80 bis 200°C unterzieht.

The invention relates to a process for the preparation of compounds of the formula I.

in which X and Y are the same or different and are hydrogen, bromine or chlorine, a methyl, methoxy, ethoxy, nitro, trifluoromethyl, carbomethoxy or carboethoxy group, A ¹ and A ^{2 are} each hydrogen, a methyl or Ethyl group and Z ¹ and Z ² in the 6- or 7-position of the heteroaromatic ring system each represent hydrogen, bromine or chlorine, a methyl, methoxy, ethoxy, carbomethoxy, carboethoxy or nitro group, which is characterized in that Compounds of formula 11

in which B is an amino or nitro group and X and Y are identical or different and have the meanings given above,

• a) in the event that B is an amino group, this 1,4-diaminobenzenes monodiazotized in an aqueous medium and with a compound from the series of 5-acetoacetylaminobenzimidazoles of the formula III
  
  in which A and Z each have the meaning given above for A ¹ and A ² or Z ¹ and Z ² , for the aminoazo compound of the formula IV
  
  couples, or
• b) in the event that B is a nitro group, X and Y have the meanings given above, but are not nitro substituents, diazotize this 4-nitroaniline and couple the diazonium compound to a benzimidazolone derivative of the formula III, where A and Z have the meanings given above , but do not represent nitro substituents and then the nitroazo compound of the formula V obtained
  
  reduced to the aminoazo compound of formula IV and
• c) the aminoazo compounds of the formula IV obtained in each case are again diazotized and coupled to an identically or differently substituted compound of the formula III and the reaction product obtained is worked up in a conventional manner and then subjected to a thermal aftertreatment at 80 to 200.degree.

Since the aminoazo compound is initially obtained by both processes, it can be used to produce specifically symmetrical and also asymmetrical disazo compounds with regard to the coupling component.

The invention also relates to new disazo compounds which have an average particle size, measured by electron microscopy, of 0,2 0.25 μm and which correspond to the formula I in which X, A ¹ , A ² , Z ¹ and Z ^{2 have} the meaning already mentioned and Y besides Bromine or chlorine preferably represents a hydrogen atom, a methyl, methoxy, ethoxy, nitro, trifluoromethyl, carbomethoxy or carboethoxy group.

Particular emphasis is placed on disazo compounds of the aforementioned type which are produced during their production in a particle size of µm 0.25 μm and which are structurally structured such that in the underlying formula IX, Y, A ¹ , A ² , Z ¹ and Z ^{2 are} hydrogen atoms mean, or in which X is a chlorine atom, or in which X and Y are methyl groups, or in which A ^{2 is} the methyl group, or in which X is a chlorine atom and Z ¹ and Z ² are chlorine atoms in the 7-position or in the 6-position Characterize methoxy groups, while in these special cases the remaining, variable, symbolized substituents each represent hydrogen atoms.

In addition to achieving very good yields, the process according to the invention is characterized above all by the fact that it provides disazo compounds which are clearly superior in terms of their particle size and particle size distribution to the compounds known from the prior art. The reworking of Tables Examples 19 and 20 of DE-OS 2 232 524 gave compounds whose particles were on average about 780 to 1 580 times larger than the average particle size of the compounds according to the invention, whose maximum particle size measured by electron microscopy was not 0.25 μm exceeded.

The compounds of DE-OS 2 232 524 are completely unsuitable as pigments because they are downsized of the coarse-crystalline particles is not possible or only possible with great effort according to the conventional methods.

The monodiazotization of 1,4-diaminobenzenes halogenated in the core is known from DE-PS 586 355. In this process, the compounds are diazotized on one side with the amount of mineral acid and nitrous acid required to diazotize an amino group, and the diazo compounds thus obtained are precipitated in solid form by adding salt.

The monodiazotization of the 1,4-diaminobenzenes of the formula 11 can also be carried out, for example, according to DE-OS 2 555 515, by the 1,4-diaminobenzene in question in water or in a mixture of water and a water-miscible solvent, for example methanol , Ethanol, acetone, dioxane, formamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, ethylene glycol, diethylene glycol dimethyl ether and / or N-methylpyrrolidone, in the pH range from 1 to 4, preferably 1.5 to 3.5, in the presence of mineral acids, for example sulfuric acid or phosphoric acid, in particular hydrohalic acids, such as hydrochloric acid, or in the presence of low molecular weight organic acids, for example oxalic acid or chloroacetic acid, in particular acetic acid, or in the presence of a mixture of a mineral acid with a low molecular weight organic acid, for example a mixture of phosphoric acid and propionic acid, or hydrochloric acid and acetic acid , or sulfuric acid and acetic acid diazotized.

The 4-nitroanilines of the formula 11 or the aminoazo compounds of the formula IV can be diazotized, for example, with alkali metal nitrites or lower alkyl nitrites with 1 to 5 carbon atoms in the alkyl group with sufficiently strong acids, in particular a mineral acid such as sulfuric acid or hydrochloric acid, but also nitrosylsulfuric acid.

The temperature during the diazotization can vary within a wide range, for example from -10 ° to + 30 ° C. However, diazotization is preferably carried out at 0 ° to + 5 ° C.

The duration of the diazotization can also be varied widely. Usually it takes 5 to 120 minutes.

In the diazotization and / or in the subsequent coupling, it may be useful, for example to achieve a favorable particle size distribution and / or to influence the reaction rate, to use an addition of surface-active agents, e.g. B. nonionic, anionic or cationic dispersants.

Such surfactants are e.g. B. anionic substances such as fatty acid taurides, fatty acid N-methyl tauride, fatty acid isethionates, alkylbenzenesulfonates, alkylnaphthalene sulfates, alkylphenol polyglycol ether sulfates and fatty alcohol polyglycol ether sulfates, fatty acids e.g. B. palmitic, stearic and oleic acid, soaps, e.g. B. alkali salts of fatty acids, naphthenic acid and Harsz acids, z. B. Abietic acid, alkali-soluble resins, e.g. B. rosin-modified maleate resins, cationic substances such as quaternary ammonium salts, N-oxides of tertiary amines or their salts, fatty amines and their ethoxylated derivatives, nonionic substances such as fatty alcohol polyglycol ethers (ethoxylated fatty alcohols), fatty acid polyglycol esters, alkylphenol polyglycol ethers and dialkyl polyglycol ethers.

The surface-active agents can be added individually or as a mixture. The amount can vary within wide limits, generally 0.1 to 20% by weight, preferably 2 to 10% by weight, based on a 100% yield.

The coupling is advantageously carried out in such a way that the coupling component is preferably dissolved in aqueous alkali hydroxide solution, precipitates again with acid and finally the coupling is carried out at 10 to 80, preferably 15 to 35 ° C. with the suspension obtained.

The coupling can also be carried out in the presence of organic solvents, e.g. B. glacial acetic acid, lower alkanols, dioxane, formamide, dimethylformamide, dimethyl sulfoxide, pyridine or N-methylpyrrolidone.

The reduction of the nitroazo compounds of the formula V, which have stable azo bridges due to their substitution, is generally carried out by conventional methods, for. B. by iron or sulfhydrate reduction or with other reducing agents, but also catalytically with hydrogen. Examples of catalytic reduction using Raney nickel from analogous nitroazo compounds which have a phenyl or pyrazolone group instead of the benzimidazolone group are described in DE-B-1266422.

Suitable solvents in which the reduction is carried out are, in addition to water, all organic solvents which are inert to reductions, for example alkanols, aprotic solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, aromatic hydrocarbons such as toluene and the various xylenes.

After the reduction has been carried out catalytically, for example using hydrogen / Raney nickel, the solvent is filtered off, the aminoazo compound is stirred with aqueous hydrochloric acid at room temperature until the metallic nickel is converted into nickel chloride and then filtered, washed salt-free and neutral and dried. If the aminoazo compound is soluble in the solvents, the catalyst is filtered off after the reduction and the aminoazo compound is isolated.

To achieve the full color strength, the reaction product is heated for some time after the second coupling, for example to reflux temperature or under pressure at temperatures above 100 ° C, optionally in the presence of organic solvents such as lower alkanols, for example ethanol or isobutanol, halogenated aromatic hydrocarbons, such as Chlorobenzene or the various dichlorobenzenes, e.g. B. o-dichlorobenzene, also dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide or in the presence of resin soap.

Particularly pure, readily dispersible and strong-colored pigments are obtained with the products according to the invention if, after coupling, the moist presscake or the dried powders are subjected to a thermal aftertreatment at 80 to 200, preferably 120 to 160 ° C. in aqueous suspension, optionally in or in the presence of organic solvents such as alcohols, especially lower alkanols with 1 to 6 carbon atoms, pyridine, glacial acetic acid, dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, halogenated aromatic hydrocarbons such as chlorobenzene or dichlorobenzenes, e.g. B. o-dichlorobenzene or nitrobenzene and / or a grinding of the pigments with the addition of grinding aids.

The pigments can also be prepared in the presence of a carrier material, for example heavy spar.

The compounds according to the invention are insoluble in water and in the customary organic solvents and, in finely divided form, are suitable for pigmenting high molecular weight organic material, it being irrelevant whether this material is used as a plastic mass, melt or in the form of spinning solutions, lacquers or printing inks is present. They can be used for pigmenting or dyeing printing inks, colored lacquers and dispersion paints and other materials such. B. paper, cellulose ethers and esters, polyamides, polyurethanes, polyacrylonitriles, polyesters such as polyglycol terephthalate, viscose, acetyl cellulose, nitrocellulose, natural or synthetic resins such. B. aminoplasts, especially urea and melamine-formaldehyde resins, alkyd resins, acrylate resins, phenolic resins, polycarbonates, polystyrene, polyvinyl chloride, polyolefins such as polyethylene and polypropylene, and polyacrylic acid esters, rubber, casein, silicone and silicone resins. They are also suitable for pigment printing on substrates, in particular textile fiber materials or other sheet-like structures, such as paper.

The pigments are very strong in color, have a particle size of - 0.25pm, are extremely resistant to the influence of chemicals, especially solvents, have perfect migration fastness, high thermal stability and very good light and weather fastness.

In the examples below,% means percent by weight.

Examples

1a) 10.8 g of 1,4-diaminobenzene were dissolved in 100 ml of water and 40 ml of 5N hydrochloric acid and cooled to 5 ° C. 50.3 ml of 2N sodium nitrite solution were added dropwise within one hour. The pH rose from 2 to 3.5. At the end of the addition, a slight excess of nitrite was found. The mixture was cooled for 30 minutes and the batch was clarified with coal and diatomaceous earth.

mit Schmelzpunkt 288 °C erhalten wurden.24 g of 5-acetoacetylaminobenzimidazolone were dissolved in a mixture of 18 ml of sodium hydroxide solution (33%) and 300 ml of water. A pH of 9 was set by dropwise addition of 10.5 ml of glacial acetic acid in 100 ml of water, the coupling component being completely precipitated. The solution of the diazo component was added dropwise to the precipitation over the course of 30 minutes, the pH of 9 being maintained by the mutual addition of about 200 ml of a 3% sodium carbonate solution. After the coupling had ended, the pH was adjusted to 7 with dilute hydrochloric acid (2%) and the mixture was heated at 95 ° C. for 30 minutes. The orange-colored precipitate was filtered off, washed free of salt and dried, where 30.3 g = (86.1% of theory) of an orange-colored powder of the formula

with melting point 288 ° C were obtained.

1b) 17.6 g of the 4-aminophenylazo compound of Example la were stirred in 100 ml of glacial acetic acid and 20 ml of hydrochloric acid (31%) for one hour. 10 ml of a 5N sodium nitrite solution were added dropwise at 10 ° C. and the mixture was stirred for a further hour with a small excess of nitrite, and 500 ml of ice water were added, the diazonium salt solution dissolving. The excess nitrite was destroyed with some sulfamic acid.

12 g of 5-acetoacetylaminobenzimidazolone were dissolved in a mixture of 200 ml of water and 10 ml of sodium hydroxide solution (33%). This solution was placed on a template of 200 ml of ice water and 6 ml of glacial acetic acid, the coupling component again failing. The mixture was then adjusted to a pH of 5 with 50 ml of 4N sodium acetate solution.

The diazonium salt solution obtained was then added dropwise to the precipitation of the coupling component within one hour and, after the total addition, the mixture was stirred for a further two hours at room temperature and one hour at 90 °. The initially red-brown pigment became orange in the process. Subsequently was sucked up, washed salt-free and dried. Yield 26.5 g (88.9% of theory) of shade 5 (CI Hue Indication Chart). The crude pigment was treated in 350 ml of dimethyl sulfoxide for 3 hours at 180 ° C., suction filtered, washed with methanol and dried. The very strong pigment of formula I obtained, in which X, Y, A ¹ , A ² , Z ¹ and Z ^{2 are} hydrogen atoms, can be processed into extremely migration-resistant printing inks, varnishes and plastics in orange shades.

2a) The 4-aminophenylazo compound prepared according to Example 1a) was also synthesized in the following way: 50 g of the 4-nitro-phenylazo compound obtained by coupling diazotized 4-nitroaniline to 5-acetoacetylaminobenzimdazolone were dissolved in 500 ml of N-methylpyrrolidone with 3 g of Raney -Nickel hydrogenated at 80 ° C and 50 bar hydrogen pressure. The orange-colored suspension was then diluted to 3 l with N-methylpyrrolidone, dissolved at 100 ° C. and filtered off from the nickel catalyst. The solution was then concentrated under reduced pressure at 80 to 100 ° C. to a volume of about 1 liter, the orange-colored product was filtered off with suction, washed with ethanol and dried. Yield 43.7 g, mp. 288 ° (94.9% of theory).

Instead of N-methylpyrrolidone, other solvents, e.g. B. dimethylformamide can be used. After the hydrogenation, the aminoazo compound can also be filtered off, stirred with water and hydrochloric acid until the nickel catalyst is destroyed and then filtered and washed free of nickel.

2) The 4-aminophenylazo compound obtained was diazotized according to Example 1b) and coupled again to 5-acetoacetylaminobenzimidazolone, giving the disazo pigment according to Example 1b).

Further disazo compounds which can be prepared by the processes according to the invention are mentioned as examples in the following table:

(Designations according to Formula I):

Claims (16)

1. A process for preparing disazo compounds of the formula I

in which X and Y are identical or different and denote hydrogen, bromine or chlorine or a methyl, methoxy, ethoxy, nitro, trifluoromethyl, carbomethoxy or carboethoxy group, A1 and A₂ each represent hydrogen or a methyl or ethyl group, and Z1 and Z2 in the 6- or 7-position of the heteroaromatic ring system each represent hydrogen, bromine or chlorine, or a methyl, methoxy, ethoxy, carbomethoxy, carboethoxy or nitro group, which comprises taking compounds of the formula II

in which B is an amino or nitro group and X and Y are identical or different and as defined above, and

a) in the case where B is an amino group, monodiazotizing these 1,4-diaminobenzenes in an aqueous medium and coupling the diazonium salt with a 5-acetoacetylaminobenzimidazole compound of the formala III

in which A and Z each have the meaning indicated above for respectively A¹ and A² or Z¹ and Z², to give the aminoazo compound of the formula IV

or

b) in the case where B is a nitro group and X and Y are as defined above but do not represent nitro substituents, diazotizing this 4-nitroaniline and coupling the diazonium compound onto a benzimidazolone derivative of the formula III where A and Z are as defined above 'but do not represent nitro substituents, and then reducing the resulting nitroazo compound of the formula V

to the aminoazo compound of the formula IV and

c) diazotizing the respectively resulting aminoazo compounds of the formula IV once more and coupling the diazonium compound onto an identically or differently substituted compound of the formula III and working up the resulting reaction product in a conventional manner and then subjecting it to a thermal aftertreatment at 80 to 200 °C.

2. The process as claimed in claim 1 wherein the coupling is in each case carried out in the presence of cationic or nonionic dispersants in amounts of 0.1 to 20, preferably 2 to 10, % by weight, based on a 100 % yield.

3. The process as claimed in claim 1 or 2 wherein the reduction of the nitroazo compound of the formula V is effected with iron or hydrosulfide or catalytically with hydrogen.

4. The process as claimed in one or more of claims 1 to 3 wherein the thermal aftertreatment is carried out in organic solvents or aqueous mixtures thereof.

5. The process as claimed in one or more of claims 1 to 4 wherein the aftertreatment is carried out at 120 to 160 °C.

6. A disazo compound of the formula I as defined in claim 1, which has an average particle size, as measured by electron microscopy, of ≤ 0.25 µm.

7. A disazo compound as claimed in claim 6, in which Y represents hydrogen, methyl, methoxy, ethoxy, nitro, trifluoromethyl, carbomethoxy, or carboethoxy.

8. A disazo compound as claimed in claim 6, in which X, Y, A¹, A², Z¹ and Z² each denote a hydrogen atom.

9. A disazo compound as claimed in claim 6, in which Y, A¹, A², Z¹ and Z² each denote a hydrogen atom and X denotes a chlorine atom.

10. A disazo compound as claimed in claim 6, in which X and Y each denote a methyl group and A¹, A², Z' and Z² each denote a hydrogen atom.

11. A disazo compound as claimed in claim 6, in which A² denotes a methyl group and X, Y, A¹, Z¹ and Z² each denote a hydrogen atom.

12. A disazo compound as claimed in claim 6, in which X denotes a chlorine atom, Z¹ and Z² each denote a chlorine atom in the 7-position and Y, A¹ and A² each denote a hydrogen atom.

13. A disazo compound as claimed in claim 6, in which X denotes a chlorine atom and Y, A¹ and A² each denote a hydrogen atom and Z¹ and Z² each denote a methoxy group in the 6-position.

14. A disazo pigment prepared by the process as claimed in one or more of claims 1 to 5.

15. Use of a disazo compound as defined in one or more of claims 6 to 13, as a pigment.

16. Use as claimed in claim 15, for pigmenting printing inks, lakes, emulsion paints, plastics, such as polyvinyl chloride and polyolefins, rubber, natural and synthetic resins, or spinning compositions and pigment printing on substrates such as textile fiber materials and other sheetlike structures, such as paper.